A serial killer is a person who murders three or more people, with the killings taking place over a significant period of time between them. The serial killers' psychological gratification is the motivation for the killings, and many serial murders involve sexual contact with the victims at different points during the murder process. The Federal Bureau of Investigation (FBI) states that the motives of serial killers can include anger, thrill-seeking, financial gain, and attention seeking, and killings may be executed as such. The victims tend to have things in common such as, demographic profile, appearance, gender or race. The FBI will focus on particular patterns that the serial killers follow throughout their murders. They will then use on the patterns they find for key clues into finding the killer along with their motives. Although a serial killer is a distinct classification that differs from that of a mass murderer, spree killer, or contract killer, there are overlaps between them.
An 1829 illustration of Irish serial killer William Burke murdering Margery Campbell
Juhani Aataminpoika, a Finnish serial killer also known as "Kerpeikkari" (which means 'executioner'), was one of the most active serial killers of the 19th century, killing as many as 12 people in 1849 within five weeks before being caught.
The 'Nemesis of Neglect': Jack the Ripper depicted as a phantom stalking Whitechapel, and as an embodiment of social neglect, in a Punch cartoon of 1888
Mug shot of serial killer, cannibal and necrophile Ottis Toole
Mass murder is the violent crime of killing a number of people, typically simultaneously or over a relatively short period of time and in proximity. A mass murder typically occurs in a single location where one or more persons kill several others.
This Airbus A320, registration D-AIPX, was destroyed while operating Germanwings Flight 9525, having been intentionally crashed into the Alps by its co-pilot, killing all 150 people on board.
The funeral for sextuple axe murder victims in Huittinen, Finland in 1943, committed by Toivo Koljonen